Forces and Motion

Worked examples (9)

• 1Match each quantity to its unit (Getting started)
• 2Mass in kg, weight in N (Getting started)
• 3Convert grams and minutes first (Getting started)
• 4Convert km/h into m/s (Building confidence)
• 5Use units to check the right formula (Building confidence)
• 6Explain why force is measured in newtons (Building confidence)
• 7A calculation with two hidden conversions (Stretch)
• 8Interpret N/kg on another world (Stretch)
• 9Significant figures and the unit mark (Stretch)

Model answers (9)

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Worked examples (9)

• 1Interpret an acceleration in words (Getting started)
• 2Calculate an acceleration (Getting started)
• 3Acceleration from rest (Getting started)
• 4Calculate a deceleration (Building confidence)
• 5A hidden km/h conversion (Building confidence)
• 6Rearrange to find a final velocity (Building confidence)
• 7Braking to a standstill (Stretch)
• 8Accelerating at constant speed (Stretch)
• 9A two-stage journey (Stretch)

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Worked examples (9)

• 1Match the line shape to the motion (Getting started)
• 2Calculate a speed from the gradient (Getting started)
• 3Find how long an object was stationary (Getting started)
• 4Describe a three-stage journey (Building confidence)
• 5Average speed for a journey including a stop (Building confidence)
• 6Plot a distance-time graph from results (Building confidence)
• 7Interpret a curved distance-time graph (Stretch)
• 8Compare two objects on one graph (Stretch)
• 9Evaluate a student's graph technique (Stretch)

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• ✓Model answer — 4SD0/1P style — extended (AO3)
• ✓Model answer — 4SD0/1P style — extended

Worked examples (9)

• 1Find a speed by direct substitution (Getting started)
• 2Rearrange to find distance (Getting started)
• 3Rearrange to find time (Getting started)
• 4Average speed for a journey with a stop (Building confidence)
• 5A journey given in km and minutes (Building confidence)
• 6A 'Show that' speed question (Building confidence)
• 7Speed and velocity for a complete lap (Stretch)
• 8Average speed across two different stages (Stretch)
• 9Evaluate a method for measuring speed (Stretch)

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• ✓Model answer — 4SD0/1P style — extended (AO3)

Worked examples (9)

• 1State the three effects of a force (Getting started)
• 2More than one effect at once (Getting started)
• 3A car at constant speed (Building confidence)
• 4Identify the resultant from the motion (Building confidence)
• 5Describe forces using the right vocabulary (Building confidence)
• 6Change of shape (Building confidence)
• 7Why a moving object needs no forward force (Stretch)
• 8Identifying what acts on what (Stretch)
• 9Match situations to effects (Stretch)

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Worked examples (9)

• 1Identify the three variable types (Getting started)
• 2Justify the choice of timing equipment (Getting started)
• 3Read a ticker tape (Getting started)
• 4Describe a full method (Building confidence)
• 5Process a results table (Building confidence)
• 6Turn results into a distance-time graph (Building confidence)
• 7Quantify the uncertainty in a stopwatch timing (Stretch)
• 8Distinguish accuracy from precision (Stretch)
• 9Devise an investigation from scratch (Stretch)

Model answers (9)

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• ✓Model answer — 4SD0/1P style — extended (AO3)
• ✓Model answer — 4SD0/1P style — extended (AO3)

Worked examples (9)

• 1Distance at constant velocity (Getting started)
• 2Distance while accelerating from rest (Getting started)
• 3Distance while accelerating from a non-zero speed (Building confidence)
• 4Total distance for a full journey (Building confidence)
• 5Average speed from the total area (Building confidence)
• 6Distance travelled while stopping (Building confidence)
• 7Estimate the area under a curve (Stretch)
• 8Distance against displacement (Stretch)
• 9Gradient and area from the same graph (Stretch)

Model answers (9)

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Worked examples (9)

• 1Read the shape of each section (Getting started)
• 2Acceleration from a line through the origin (Getting started)
• 3Gradient of a line that does not start at the origin (Building confidence)
• 4Plot a velocity-time graph from results (Building confidence)
• 5Compare accelerations from steepness (Building confidence)
• 6A negative gradient (Building confidence)
• 7Full description of a multi-stage journey (Stretch)
• 8Acceleration at an instant from a curve (Stretch)
• 9Telling the two graph types apart (Stretch)

Model answers (9)

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Worked examples (9)

• 1Final speed from rest (Getting started)
• 2Final speed with a non-zero start (Getting started)
• 3Braking distance with a negative acceleration (Building confidence)
• 4Rearrange to find the acceleration (Building confidence)
• 5Choosing between the two relationships (Building confidence)
• 6Free fall from a height (Building confidence)
• 7Why doubling the speed quadruples the braking distance (Stretch)
• 8Two-stage journey (Stretch)
• 9Working backwards to the initial speed (Stretch)

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Worked examples (9)

• 1Contact or non-contact? (Getting started)
• 2Name a force and give its direction (Getting started)
• 3Forces on a falling ball (Building confidence)
• 4Draw a labelled force diagram (Building confidence)
• 5Attraction and repulsion rules (Building confidence)
• 6Forces on a floating object (Building confidence)
• 7Read the motion from arrow lengths (Stretch)
• 8Naming forces on a slope (Stretch)
• 9Spotting forces that do not exist (Stretch)

Model answers (9)

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Worked examples (9)

• 1Sort quantities into scalars and vectors (Getting started)
• 2Define the two terms (Getting started)
• 3Forces acting the same way (Getting started)
• 4Forces acting in opposite directions (Building confidence)
• 5When the resultant opposes the motion (Building confidence)
• 6Why direction matters for a force (Building confidence)
• 7Distance against displacement (Stretch)
• 8Three forces using signs (Stretch)
• 9Resultant force into F = ma (Stretch)

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Worked examples (9)

• 1Which way does friction act? (Getting started)
• 2Define friction and its energy effect (Getting started)
• 3Useful and unhelpful friction (Getting started)
• 4Reducing friction (Building confidence)
• 5Friction inside a resultant force (Building confidence)
• 6Why a cruising car still needs its engine (Building confidence)
• 7Why a vehicle has a top speed (Stretch)
• 8Friction on a slope (Stretch)
• 9A world without friction (Stretch)

Model answers (9)

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Worked examples (9)

• 1Direct substitution (Getting started)
• 2Find the resultant, then the acceleration (Getting started)
• 3Converting units before substituting (Building confidence)
• 4Rearrange to find the mass (Building confidence)
• 5A braking force (Building confidence)
• 6Proportionality without numbers (Building confidence)
• 7Mass from a given weight (Stretch)
• 8Combine F = ma with the equations of motion (Stretch)
• 9Why a loaded vehicle accelerates more slowly (Stretch)

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Worked examples (9)

• 1Calculate a weight (Getting started)
• 2Find a mass from a weight (Getting started)
• 3Mass and weight compared (Getting started)
• 4Weight on the Moon (Building confidence)
• 5Find g on another planet (Building confidence)
• 6Weight to mass, then F = ma (Building confidence)
• 7Why g in N/kg equals the free-fall acceleration (Stretch)
• 8Hammer and feather on the Moon (Stretch)
• 9What bathroom scales actually measure (Stretch)

Model answers (9)

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Worked examples (9)

• 1The two parts defined (Getting started)
• 2Calculate a thinking distance (Getting started)
• 3Total stopping distance (Getting started)
• 4Sort the factors (Building confidence)
• 5Braking distance from v² = u² + 2as (Building confidence)
• 6Why a loaded vehicle stops in a greater distance (Building confidence)
• 7Why doubling the speed more than doubles the total (Stretch)
• 8Stopping distance on a velocity-time graph (Stretch)
• 9Applying it to road safety (Stretch)

Model answers (9)

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Worked examples (9)

• 1Name the forces on a falling object (Getting started)
• 2The moment of release (Getting started)
• 3The full three-stage explanation (Building confidence)
• 4The velocity-time graph (Building confidence)
• 5Comparing the forces numerically (Building confidence)
• 6When the parachute opens (Stretch)
• 7Graph with a parachute opening (Stretch)
• 8Feather and stone on Earth and the Moon (Stretch)
• 9What changes the terminal velocity (Stretch)

Model answers (9)

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Worked examples (9)

• 1Calculate an extension (Getting started)
• 2State Hooke's law (Getting started)
• 3Elastic or inelastic? (Getting started)
• 4The required practical method (Building confidence)
• 5Proportionality with a distractor (Building confidence)
• 6Interpret a force-extension graph (Building confidence)
• 7Spring, wire and rubber band compared (Stretch)
• 8Elastic limit versus limit of proportionality (Stretch)
• 9Safety and accuracy in the practical (Stretch)

Model answers (9)

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